The present invention relates to a semiconductor device, an RC-IGBT, and a method of manufacturing the semiconductor device, and relates to, for example, a semiconductor device mounted on electric vehicles, other mechanical equipment or the like that use motors, an RC-IGBT, and a method of manufacturing the semiconductor device.
A motor driving power device is mounted on electric vehicles, other mechanical equipment or the like that use motors. The motor driving power device includes, for example, an insulated gate bipolar transistor (hereinafter, it will be called an IGBT) and a free wheeling diode (hereinafter, it will be called an FWD) used together with the IGBT.
A Reverse-Conducting IGBT (hereinafter it will be called an RC-IGBT) is composed of an IGBT and an FWD formed in a single chip. In the RC-IGBT, an n type cathode layer is formed on a rear surface of the FWD. Then a cathode layer of the FWD that has been formed is bonded to both a collector layer of the IGBT and electrodes on the rear surface. In this way, the RC-IGBT is formed to be a single chip and has been practically used for a small-capacity chip targeted for home appliances and the like.
U.S. Pat. No. 9,041,050 discloses, in the specification, an Injection Enhancement (IE) type trench gate IGBT composed of first linear unit cell regions having linear active cell regions, second linear unit cell regions having linear hole collector regions, and linear inactive cell regions disposed between the first and second linear unit cell regions. This document discloses that, according to the aforementioned structure, reduction of the switching speed caused by IE effects can be prevented.
Japanese Unexamined Patent Application Publication No. 2011-216825 discloses a semiconductor device in which a diode region and an IGBT region are formed, and in which a lifetime controlled region is formed in a semiconductor layer of the diode region. The lifetime controlled region extends continuously in such a way that it enters a part of the IGBT region from a boundary between the diode region and the IGBT region. This document discloses that, according to the aforementioned structure, both an ON voltage and a reverse recovery charge (Qrr) are improved.
Japanese Unexamined Patent Application Publication No. 2016-082097 discloses an RC-IGBT including a plurality of dummy trenches and a grid-structured gate trench located between the plurality of dummy trenches. In a cell region surrounded by the grid-structured gate trench, an emitter region, a first anode region, a first barrier region, and a first pillar region are formed. The first pillar region is configured to extend along a thickness direction of a semiconductor substrate, be in contact with a front surface electrode, and be connected to the first barrier region. According to the aforementioned structure, a low ON voltage, a low gate capacitance, and a stable operation of a pn diode are achieved.
Japanese Unexamined Patent Application Publication No. 2015-165541 discloses a semiconductor device including a diode region and an IGBT region, in which the diode region includes a p-type anode region connected to an anode electrode by an Ohmic contact and a plurality of n-type pillar regions connected to the anode electrode by Schottky contacts. This document discloses that, by making an on-resistance of a first pillar region with respect to the anode electrode higher than an on-resistance of a second pillar region with respect to the anode electrode, gate interference can be suppressed.
Japanese Unexamined Patent Application Publication No. 2013-247248 discloses forming a field stop region by ion-implanting selenium into a rear surface of a semiconductor substrate, then selectively ion-implanting phosphorus and boron into the field stop region, to thereby form an n+ type region in a diode and form a p+ type region in an IGBT. This document discloses that, according to this manufacturing method, the breakdown voltage can be improved and the leakage current can be reduced.
Japanese Unexamined Patent Application Publication No. 2013-197306 discloses an RC-IGBT in which a first lifetime controlled region is formed on a collector side in an IGBT region, whereby the lifetime of carriers on an emitter side is made long and that on a collector side is made short, and a second lifetime controlled region is formed on an anode side in an FWD region, whereby the lifetime of carriers on an anode side is made short and that on a cathode side is made long. According to the aforementioned structure, the switching characteristic is improved.
Japanese Unexamined Patent Application Publication No. 2013-197122 discloses an RC-IGBT including an IGBT region having a base layer provided on one surface of a substrate and a diode region having an anode layer having a higher impurity count in a portion of the base layer. This document discloses that recovery characteristics of a diode and ohmic contact characteristics are improved by making the area occupied by the trench in the diode region different from the area occupied by the trench in the IGBT region.